In blocked isocyanates, the blocking agent is dissociated by heat and the isocyanate group is regenerated, and blocked isocyanates have a long pot life and excellent processability, and therefore often used as a curing agent for polyurethane resin, such as coatings and adhesives, produced by curing a polyol component (main component) and an isocyanate component (curing agent).
Patent Document 1 (ref: Examples 1 to 5) proposed such blocked isocyanates, for example, a blocked isocyanate produced by allowing an isocyanate group of hexamethylene diisocyanate trimer to react with 30 to 70 mol % of methyl ethyl ketoneoxime (MEKO) and 30 to 70 mol % of 3,5-dimethylpyrazole (DMP) as blocking agents.